Laser emission sources that are tunable in wavelength have been known for several years, in particular laser sources having distributed Bragg reflectors (DBR lasers).
In this respect, reference may be made to the following publications:
1! "High performance tunable 1.5 .mu.m InGaAs/InGaAsP multiple quantum well distributed Bragg reflector laser", T. L. Koch, U. Koren and B. I. Miller, Applied Physics Letters, 53 (12), 1988, p. 1036; and PA1 2! "Focused ion beam lithography of multiperiod gratings for a wavelength-division-multiplexed transmitter laser array", I. M. Templeton et al., Journal of Vacuum Science and Technology, Part B, Vol. 13, No. 6, November 1995, pp. 2722-2724. PA1 3! "Control of lasing wavelength in distributed feedback lasers by angling the active stripe with respect to the grating", W. T. Tsang, R. M. Kapre, R. A. Logan and T. Tanbun-Ek, IEEE Photonics Technology Letters, Vol. 5, NO. 9, 1993, pp. 978-980, has proposed a component comprising, on a common substrate, both a constant pitch Bragg grating and a plurality of buried ribbons forming active layers for laser emission, the various ribbons being inclined at different angles relative to the diffraction grating.
Making such components nevertheless requires implementing several stages of epitaxial regrowth, and is therefore complex.
Also known, in particular from U.S. Pat. No. 4,993,036, are laser-emitting components that integrate on a common substrate a plurality of laser-emitting sources having Bragg gratings with different periods.
Nevertheless, implementing a plurality of different-pitch gratings at micrometer scale and disposed beside one another is technologically complicated.
More recently, the following publication
The emission wavelengths of the various sources constituted in that way varies with the angle of inclination between the diffraction grating and the ribbon forming the active layer.
Nevertheless, those components suffer from fiber connection problems.
The materials used for fabricating them have refractive indices of the order of 3.5. Given that the various ribbons forming active layers are at different inclinations relative to the cleavage plane of the substrate, refraction gives rise to large amounts of variation in the angles at which the emitted beams are output into the air relative to the normal to the cleavage plane of the component.
It is therefore necessary to provide a different fiber inclination for each emitted wavelength.